remington model 7 magazine length, help

I have a .223 model seven that I am getting rebarreled in 6x45mm (6mm-223) currently. The inside mag length is only ~60mm which is no good, it's far too short - dummy rounds that I have loaded with the hornady 87gr HPBT, the 90gr NBT etc, all show me that I need at least a 65mm long mag - and closer to 70mm would be preferable to get the optimum seating depth so that I don't have half the bullet taking up a lot of powder space.

I have considered getting an -08 length mag box/follower from brownells, as this is ~20mm longer on the inside, but it most likely won't work properly - I can only get one 6x45mm round to sit in the mag of the .270 model 700 that I have handy, after that they pop out, or if I can get them to sit in there, they double-feed due to the follower shape.

The way I am looking at it right now, my options are:

* Try to remove, shorten and re-weld the mag block in the .223 model 7 mag so that there is more internal space - probably a difficult and poor option

* Use an -08 length box and follower, and accept that it will only be a 2 round rifle, one in the chamber and one in the mag - I wouldn't be happy with this for a hunting rifle really.

* Get a custom .223 case follower made, in the -08 mag box length - probably the best option, although costly.

Any other suggestions would be welcomed, I need to find whether there is a workable solution or not before I get the throat cut in the new barrel. If I can't find something that works I may just have to use it with the mag it has and seat the bullets deep, but to me it's not satisfactory to have to compromise like that on a custom rifle.